Electron Paramagnetic Resonance (EPR) Oxygen Images (EPROI) have been shown to provide quantitative localized pO2 images of animal tumors including several in syngeneic mice, and in rats, and rabbits. The parent grant has demonstrated statistically significant sharpening of the 50% tumor control dose with the addition of the information provided by the fraction of EPROI voxels less than 10 torr (HF10). Specific aims for the current grant cycle: 1) Determining the relation between the localized oxygen information from the EPROI and pimonidazole retention, induction of hypoxia proteins and single biopsy hypoxic fraction. 2) Treatment of murine tumors to TCD50 after oxygen images and determining the predictive effectiveness of the HF10 and other EPROI tumor statistics and 3) Using the HF10 from EPROI to dose paint regions of hypoxia with IMRT to determine the impact of the EPROI on cure of mouse tumors. This work will validate quantitative oxygen imaging in optimizing radiation delivery and stimulate the development of oxygen imaging for treatment of human tumors. The funding of the Research Specialist position will enhance the technology required for the success of the parent grant through introduction of conformal beam radiation protocol and develop technology for pH and redox status guided intensity modulated radiation therapy in mouse tumors. Such support will provide sufficient time to secure funding between grant cycles.